/Engine/Source/Runtime/HeadMountedDisplay/Public/IXRTrackingSystem.h
Computes a transform to convert from 'Floor' origin space to 'Eye' origin space. Useful when changing between the two different TrackingOrigin spaces. Invert the transform to get the opposite.
True if the transform was successfully constructed.
bool GetFloorToEyeTrackingTransform ( FTransform & OutFloorToEye ) const